Ocular prosthetic devices that simulate the appearance of a natural eye are known which attempt to faithfully reproduce the physical features of such a natural eye. Often such prosthetic eyes have a simulated iris of a color and pattern so as to match the complementary natural eye. Such prosthetic eyes typically incorporate an iris image, which nearly matches the complementary natural eye in color and pattern, and a simulated pupil. The iris image is produced on a white prosthetic shell adapted to be covered with a clear medium. The simulated pupil is of fixed size and does not react to light intensity, thereby detracting from the appearance of a natural eye. Attempts have been made to simulate a pupil which adjusts to light level so as to provide an appearance of pupil dilation and contraction in response to ambient light. One such approach is described in Danz, U.S. Pat. No. 4,272,910, which discloses a transparent annular display, located in front of an iris image, of a size approximating that of a fully dilated pupil. The transparent annular display is constructed such that it is darkened when activated to therefore provide the appearance of a fully dilated pupil. A light sensor, also having a darkened appearance, is located at the center of the transparent annular display to sense ambient light. The light sensor is of a size to provide the appearance of a fully contracted pupil. Based upon the signal from the light sensor, the transparent annular display can be darkened to give the appearance of a fully dilated pupil, by obscuring the centermost portion of the iris, or deactivated and made transparent such that the full iris image is seen and the darkened light sensor in the center appears as a fully contracted pupil.
Since the transparent annular display, however, is located in front of the iris image, the display tends to affect the appearance of the iris image even when it is deactivated. Further, as the display is activated to provide the appearance of a fully dilated pupil, such a display may not match the appearance of the pupil of the natural eye in moderate ambient lighting environments. Further, Danz does not suggest varying the display under a continuum of ambient lighting conditions to adapt to a variety of lighting environments.
Other prior art prosthetic eyes have not been satisfactory by reason of difficulty of manufacture, short useful life, poor natural appearance, or high cost. The following patents show prior art prosthetic eye constructions. Gordon et al., U.S. Pat. No. 3,905,130, discloses an opthalmological device including an eye mechanism using photographic-type diaphragms for simulating an iris. Gordon et al., however, utilizes a mechanical structure to alter pupil diameter, not an electronic display. Kulis, U.S. Pat. No. 4,637,159, teaches a simulated eye construction including a convex outer lens portion and a transparent second lens member having a reflecting surface behind for reflecting light. Kulis, however, does not teach pupil diameter adjustment. Secrist, U.S. Pat. No. 5,037,344, suggests an artificial doll eye which allows light to travel through a lens some distance into a solid, transparent light shaft in the center of the lens and pupil to give the impression of a real human eye. Secrist, however, does not suggest actual manipulation of pupil diameter. Su, U.S. Pat. No. 5,004,443, shows an electronically operated doll eyeball which uses LEDs to simulate movement of the pupil image, however does not disclose dynamically changing the apparent size of the pupil image.
It would be beneficial, therefore, to provide a prosthetic eye in which the iris color and pattern are consistent regardless of the simulated pupil size, and which provides a simulated pupil size adaptable to a variety of ambient lighting environments.